UK light heavyweight Buatsi secured a victory yet underwhelming start to life under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a split decision in a competitive 10-round contest at the boxing arena.
But Parker had his moments, landing some telling individual punches in a fight where the styles failed to mesh, with excessive holding disrupting the contest.
The officials judged it 96-94 for to Buatsi, with the remaining official a 95-95.
"It wasn't my greatest display but what defines champions? They prevail," Buatsi commented in the ring as he was greeted with negative reactions from the crowd.
The Londoner bounced back after his first professional defeat - an thrilling contest with Callum Smith in February - to claim a 20th career victory.
Various analysts thought the challenger, thirty-one, deserved the win but the contender endured the second defeat of his 28-fight professional journey.
The Champion Earns Win in Uneventful Affair
The fighter's advancement has slowed in recent times through management issues and long spells of inactivity.
Once tipped as the next star of the British fight scene, he now finds himself trying to achieve expectations - possibly in what feels like a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors willing to be aggressive in a tentative early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand mid-fight, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, the underdog had kept it close, making life awkward for the favorite, who worked behind a solid defense to narrowly win the better periods.
The spectators' acceptance decreased during frequent holding, with the challenger slipping to the canvas various instances during grappling.
The underdog closed well, but many rounds were hard to judge. However, former world champion the boxing analyst - providing analysis for the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just one round.
The victor progresses, but with the likes of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Tribute Motivates All-Manchester Battle
In the supporting bout, Arthur beat Rea by divided decision in a terrific all-Manchester battle to capture the European light-heavyweight title.
The arena became quiet for a deeply poignant homage ahead of the contest as a bell ceremony tolled in honor of Manchester's own Hatton, who succumbed at age 46 in last month.
It was the first major televised match card in the urban center since Hatton's passing. As the final chime faded, the quiet transitioned to a chant of "only one Hatton".
The fighting inside the ropes reflected the sentiment. The eventual winner was floored by a significant blow directly to the jaw in the early round, getting up unsteadily to his feet on the eight count.
But the Manchester United-red attire of the fighter soon came forward again. On the opposite side, the opponent - in rival City blue - was marked up soon, heavy swelling appearing under his eye as the pair exchanged punishing blows.
Rea, twenty-seven, landed power punches but Arthur, 34, responded in kind with stinging uppercuts as the pace hardly diminished over the full distance.
The victor narrowly won the verdict with official scores of 114-114, narrow lead and 115-112, but both fighters were persistent and brave, exactly what their idol Hatton stood for.
